2006 CASCON Zhuang Guo, José Nelson Amaral,Duane Szafron and Yang Wang, Utilizing Field Usage Patterns for Java Heap Space Optimization, to appear in 16th Annual International Conference on Computer Science and Software Engineering (CASCON), October 2006, 8 ms., abstract or pdf.

This research studies the characteristics of field usage patterns in the SpecJVM98 benchmarks. It finds that multiple object instances of the same class often exhibit different field-usage patterns. Motivated by this observation, we designed a heap compression mechanism that classifies object instances at runtime based on their field-usage patterns and eliminates unused fields to save space. To achieve the maximum space savings while minimizing the space and time overhead, our design combines three interrelated techniques in a novel manner: runtime object instance classification, field virtualization, and bidirectional object layout. An experimental evaluation reveals that this mechanism can reduce the maximum heap occupancy of SpecJVM98 benchmarks by up to 18% and 14% on average while keeping the application execution overhead low.